# Micheli 2018: Non-gravitational acceleration in the trajectory of 1I/2017 U1 ('Oumuamua) > Marco Micheli, Davide Farnocchia, Karen J. Meech et al., 2018. 11 records on Mysteries Department cite it. The central anomaly, the measurement every… Source: https://mysteriesdept.com/sources/SRC0CSKB4A401DZ/non-gravitational-acceleration-in-the-trajectory-of-1i-2017 Publisher: Mysteries Department Licence: CC BY 4.0 (credit Mysteries Department and link the page) --- [Sources](https://mysteriesdept.com/sources)[1I/'Oumuamua](https://mysteriesdept.com/mysteries/oumuamua)Micheli 2018 **0** # Non-gravitational acceleration in the trajectory of 1I/2017 U1 ('Oumuamua) Marco Micheli, Davide Farnocchia, Karen J. Meech et al., 2018. _Nature_. Reports, at 30-sigma significance, a non-gravitational acceleration in the astrometry from 14 October 2017 to 2 January 2018, including Hubble positions. All data fit once a radial acceleration scaling as the inverse square or inverse of heliocentric distance is added. Rules out radiation pressure for an ordinary body, drag, solar-wind forces on a magnetised object, a binary, and a photocentre offset, and finds comet-like outgassing the physically viable explanation if the body has comet-like thermal properties. Nature 559, 223-226. **1I/'Oumuamua** Articledoi: **[10.1038/s41586-018-0254-4](https://doi.org/10.1038/s41586-018-0254-4)** Checked against the original0 ## What it's used for here The central anomaly, the measurement every explanation must reproduce. ## Cited by on this site 11 records [Outgassing of water or another undetected ordinary volatile from an icy body, below the limits of every…](https://mysteriesdept.com/mysteries/oumuamua/answers/ANS0CSKC0W61KZV/outgassing-of-water-or-another-undetected-ordinary-volatile) Answer ANS [The acceleration is an artefact of the astrometry or the orbit fit, not a real force.](https://mysteriesdept.com/mysteries/oumuamua/answers/ANS0CSKC86J73W1/the-acceleration-is-an-artefact-of-the-astrometry-or-the) Answer ANS [1I/'Oumuamua](https://mysteriesdept.com/mysteries/oumuamua/artifacts/ART0CSKCV7Y2C6C/1i-oumuamua) ART [Micheli et al. 2018 source data (astrometric residuals with and without the acceleration; comet A1 comparison)](https://mysteriesdept.com/datasets/DAT0CSKCS1M6WJ1/micheli-et-al-2018-source-data-astrometric-residuals-with) Dataset DAT [Outgassing was the only mechanism the discovery team found physically viable, if the body had comet-like…](https://mysteriesdept.com/mysteries/oumuamua/evidence/EVD0CSKC1407J6K/outgassing-was-the-only-mechanism-the-discovery-team-found) Evidence EVD [Radiation pressure on an ordinary rocky body is far too weak to give the measured acceleration.](https://mysteriesdept.com/mysteries/oumuamua/evidence/EVD0CSKCD2T4S3Y/radiation-pressure-on-an-ordinary-rocky-body-is-far-too-weak) Evidence EVD [The discovery team tested and excluded a photocentre offset and a binary.](https://mysteriesdept.com/mysteries/oumuamua/evidence/EVD0CSKC8EC6VY9/the-discovery-team-tested-and-excluded-a-photocentre-offset) Evidence EVD [Hubble's last positions of the object](https://mysteriesdept.com/mysteries/oumuamua/events/EVT0CSKBWQC376W/hubbles-last-positions-of-the-object) EVT [Marco Micheli](https://mysteriesdept.com/mysteries/oumuamua/people/FIG0CSKBRAR05DH/marco-micheli) FIG [1I/'Oumuamua](https://mysteriesdept.com/mysteries/oumuamua) The mystery article MYS [What pushed 'Oumuamua away from the Sun?](https://mysteriesdept.com/mysteries/oumuamua/questions/QST0CSKBZDA67JF/what-pushed-oumuamua-away-from-the-sun) Question QST ## Cite it ``` Micheli, M., Farnocchia, D., Meech, K. J., Buie, M. W., Hainaut, O. R., Prialnik, D., Schörghofer, N., Weaver, H. A., Chodas, P. W., Kleyna, J. T., Weryk, R., Wainscoat, R. J., Ebeling, H., Keane, J. V., Chambers, K. C., Koschny, D., & Petropoulos, A. E. (2018). Non-gravitational acceleration in the trajectory of 1I/2017 U1 ('Oumuamua). Nature. https://doi.org/10.1038/s41586-018-0254-4 ``` [Read it free at doi.org](https://doi.org/10.1038/s41586-018-0254-4) Key **SRC** 0CSKB4A401DZ Kind Journal article Rights The publisher's Kept 27 Oct 2026, for editors Checked Against the published article Added by [apollo](https://mysteriesdept.com/u/apollo) The record Bibliographic records are CC0. Take this one as CSL-JSON, BibTeX or RIS. [CSL-JSON](https://mysteriesdept.com/sources/SRC0CSKB4A401DZ/non-gravitational-acceleration-in-the-trajectory-of-1i-2017/csl.json)